Thursday, May 31, 2007

54 TVs' consumption compared - TV power consumption - CNET reviews

Cnet has power measurements for 54 TVs.

54 TVs' consumption compared - TV power consumption - CNET reviews: "TV power-saving tips"

Bedfan saves energy by localized cooling

As mentioned previously only cooling the area surrounding you saves energy because you aren't cooling your whole house. One product that touts this is the Bed fan for cooling your bed area while you sleep. I'm not sure how well it works but it's nice to see that products are being touted for saving energy by localized cooling.


Bedfan Bed Fan sleep cooler save energy: "We are doing this for several reasons. One is to make it simpler for people to make their purchase without the full payment up front. Once you have fully tuned the Bedfan® to the most efficient setting you should be able to recover your investment in a very short period of time, Some people are able to recover their cost within a month. See our savings table for further explanation."

Saturday, May 26, 2007

home built a/c and other alternatives -- non peak electrical usage

Arwen posted in the comments on "fans & a/c" this cool homemade air conditioner that uses ice as the source of the "cool"

In a similar genre are evaporative cooling devices are called "swamp coolers" and misting devices like "cool zones" (You'll see them at football games spraying a mist of water on the players on the sidelines)

Here are my thoughts:

Indeed those certainly look like they'd keep you cooler than a fan (basically it's using ice as a source of coolness and running the cold via copper piping across the fan so that the air the fan is circulating is cold).

However, where does the ice come from? The cost of the electricity to generate the ice has to be figured in to account. Ice is quite expensive to make or buy, and you lose a fair amount to melting in the cooler and inefficient heat transfer. So while you may have a free source of ice, some power plant somewhere is powering the compressor used to create that ice.

However, on the plus side, very few materials were used to build this "a/c" system so you aren't wasting a buch of resources building a fancy compressor motor for an a/c unit. Also, the ice can be generated at night, when power plants that run all the time (like hydroelectric or nuclear) are producing energy that may not be being used. If you pay your electricity bill on a time dependent basis this can save you a lot of money to shift your electricity use to night time. There are commercial a/c systems that are being built to take advantage of this. They will generate "cool" at night and store it in some form of ice or cold store and then blow air over it during the day. See more at cnet from may 2007 Throwing cold water on energy-hog air conditioners
from 2006 Ice-powered air-conditioner could cut costs

Will all this non peak electricity evaporate as more and more people get time based billing and start using products like this? There's talk of charging plug in hybrid cars at night for the same benefit. Also schemes exist like compressing air in to caves at night and releasing the pressure during the day to generate power (by shifting power from night to day). But the fact of the matter is that most of our power comes from coal and fossil fuels. Which go away whenever they are burned day or night. So if our power plant is one of those, we need to use the most efficient cooling methods rather than shifting the electricity use somewhere else.

Also perhaps the biggest take away point from the instructables is that you are cooling your immediate area, not the whole room. Bingo! That's going to save a huge amount of energy even if the method is slightly inefficient.

What do other people think?
If you don't have night time electricity going to waste that can be used to generate the ice, how efficient is ice creation vs. a home a/c system?

Sunday, May 20, 2007

Power measurement of the day - Treadmill

Landice Cardio Trainer L8 (Big treadmill)
off 2 watts
idle 12 - 13
on 46-48 (0.5mph no load)
51-151 (0.5mph 225lb load walking)
113-123 (3mph no load 113-123)
119-457 (225 lb load)
200-209 (6mph 200-209 no load)
220-590 (6mp 225lb load)
518-923 (9mp 225lb load)
342-356 (9mp no load)

It's probably best not to worry about the treadmill though. Knowing most americans you'll end up carrying it up to the attic soon enough. :)

Actually since we are relativistic here, sure not using the treadmill would save energy, but what's the flip side? how much energy is wasted by not using the treadmill? Anybody have power figures on what those crash cart paddles use in hospitals?

Tho on the flip flip side, treadmill might increase your metabolism causing you to eat more food which uses energy resources... gahhh....

Though I feel confident in declaring a victory to.....
The treadmill. Keep it, it's pro environment.


hook up your treadmill as a generator and power your house like this hong kong gym :)

Computer power supplies

jils (who has an excellent software development blog at notes an efficient power supply can make a big difference. By the chiming in with this sort of thing is greatly appreciated. The blog format is not ideal it was just easy way to put stuff the web, but I really hope that people chime in ways of measuring and reducing energy usage, and for evaluating environmental decisions.

One other item of note on quantitating computer power usage, the power supply rating (say 350Watts) is the output number, which means you have to factor in the efficiency rating to determine how much power it will conceivably draw. While most computers don't draw the peak amount, you may be wanting to know this for peak loading if you are sizing a UPS or solar system.

So a 80% efficient 350W power supply can draw 350/.8 = 437.5 watts and a 60% efficient power supply can draw 583 watts. That one component can make a big difference especially if you leave your computer on all the time. Keep in mind that the .2 or .4 "inefficient" part of the power supply all goes to heat which means you have to run your a/c more.

Computer power supply efficiencies are actually variable based on load. So really in the end to know how much power you're drawing you have to measure it.

So like I always say, there's lots of things you can do to reduce your energy usage, but how do we evaluate the choices with our own constrained resources (read: wallet)

Is it better to spend an extra $100 to get a 80% efficient supply or is better to spend an extra $100 to get a lower power processor? The lower power CPUs out today are design to be in a 65 watt (thermal design envelope) meaning that they aren't meant to put out more than that. Generally that applies to a range of processors so the fastest ones will put out 65 watts (which is the same as the amount of power they draw) and the slower lower power ones might be in the high 50s. The regular power processors range from 80 as high as 120 watts (though those are typically workstation or extreme processors which aren't in the same purchase category). So lets say you save 30 watts by going with the low power cpu. For a 350 w power supply the difference between 70% efficient (about average) and 80% efficient is 125 watts.

Score one for the power supply.

Saturday, May 19, 2007

fans and a/c

As it starts to warm up and you think about turning on the a/c try a fan instead.

Patton U2-2003 fan
off 0
peak 314
high 171-176
medium 129-132
low 141-144

E20739 20" box fan 80 watts(starting up)
high 76-77
medium 57
low 42

That's a lot better than 900 watts or more for an air conditioner.
Windchaser PACR9 (SA12059 WA9000-ER) Portable air conditioner 9000BTU 868-906 watts

For those of you with a whole house a/c try opening a window. Greenhouse effect may make it warmer inside than out.

Readers, come to my rescue! Explain to me what the heck the fan setting on my thermostat does. It doesn't seem to do anything best I can tell. Ideally it would just bring in outside air instead of running the compressor, when the outside air is colder than inside, but that doesn't seem to be the case!

Friday, May 18, 2007

Power Measurement of the day: Canon EOS 1Ds

The canon EOS 1Ds is a digital SLR 11 megapixel camera. It has a NiMh battery. However it can also run off a/c. I tested it in this a/c mode.

Just on and not doing anything it uses 1-2 watts.
Holding down the shutter release and shooting continuously it uses 18 watts of power.
The power consumption of writing to the compact flash card or shooting slowly is around 8 watts.

Kitchen related power use

Other than lighting and air conditioning, some of the biggest power users in your house are found in your kitchen (though according to this TVs are going to pass the kitchen up! )

The big items in the kitchen:

Refrigerator -- probably the biggest, new ones are more efficient than old, draws a minimal amount of power all the time, and more when for a while after you open the door to bring temp back down

Dishwasher -- has to heat water to a very high temperature and swish it around

Electric Stove -- has to get very hot :)
A gas stove doesn't use much electricity, but it does use gas (These are profound illuminations of energy use....I know)

Both stove types will incur increased air conditioning use in the summer as well.

The microwave is a more efficient heater because while it has a very high power draw, it takes less time. My theory is that convection ovens are also more efficient than standard because the energy used to run the fun, is probably less than the energy saved by the even distribution of heat and resulting less cook time.

Some measurements I have made around kitchens:
Braun type 4045 coffee grinder 0 139 (setting 3) -- 99-103 (setting 1) 71-73

Delonghi Alfredo XU120 toaster 657 (broil) light toast (1248) 630-640 (broil) 1200 (light toast) .04 kwh used for light toast cycle

Cuisinart KUA-17 kettle 0 1352-1369

samsung MW5370W microwave 0 1306-1320

A good source of appromixate power use is

So while .04 kwh used for light toast is small it's the bigger items in the kitchen that I haven't measured that make most of the difference.

Practical tips:

Run your dish washer on energy saver dry
Buy an efficient refrigerator
Don't leave the refrigerator door open!

Thursday, May 17, 2007

AMD Cool n quiet

A friend of mine (jils) built a home theater pc with the goals of it being quiet and cost effective. Quiet computers are achieved by eliminating fans, which implies having low heat, which means low power.

With AMD CPUs there is a software program called cool n quiet, that will reduce the clock speed of the processor when it's not being used. On intel computers this is generally known as speedstep and doesn't usually require software.

He describes his home theater pc designed for watching HDTV on his 720P LCD rear projection tv like this:

based on an A64 3500+ Winchester CPU So it is not one of the super low-power jobs, but still much cooler than a P4 of that generation.

The Mobo chipset is an Nvidia 6150 with integrated Geforce graphics sharing the onboard RAM.
80 Gig Seagate Barracuda 7200.7 IDE HDD
300 Watt Antec PS
Avermedia analog Tuner Card
Dvico Fusion HD Tuner Card

He reports the following power usage without the software:
All Measurements in Watts. AMD Cool and Quiet NOT Enabled
S3 Standby: 6
Idle: 81-82
High Load: 98 W (720p x.264 Playback inside of the MCE Interface).

With Cool & Quiet software running, the 3500+ clocks down to 1000Mhz and up from there depending on load.

IDLE: 69 Watts
Watching 640px XviD: 69 Watts (no extra CPU needed for viewing).
Load: 720p x.264 MKV: 90-96 Watts

So he saves 12 watts on idle, and a few watts when it's decoding hdtv. Also interesting to note that the system is effectively idling when it's playing a dvd, because the cpu is still fast enough at the lower clock speed so it doesn't need to increase the speed (and thus power)

The intel core 2 duo chips are very cood at power reduction (probably better) but they can be hurt by the chipset taking up a lot of energy.

The AMD chip jils chose was very cheap, and thus also there's implied environmental savings as it probably took less silicon to produce.

Note that letting his computer go to standby (from which windows media center can wake up to record shows) saves a tremendous amount of power and still provides instant on.

He mentions S3 state which is a lower power mode of standby.

Note that screensavers don't save energy! only having your computer turn off your monitor, hard disks or go to standby (best) does! hibernate is even better.

However if you have a AMD computer look in to cool n quiet to reduce your power usage while you are using your computer!

Tuesday, May 8, 2007

Upcoming topics

Some things I've been meaning to post about:

Another downside of CFL (Compact Fluorescent Lightbulbs) -- They need to be recycled because they contain toxic chemicals, where as incandescents can just be thrown away

Eco-mode indicator in hybrids encourages efficient driving and is moving to all toyota cars in future

high efficiency incandescents from GE

should I be running folding @ home?

how to reduce your computer power usage

discussion of new biofuels (unintended effects, costs of production)

rise of the evaluation of computers based on power efficiency

discussion of the power saving black version of google

Anybody have any other topics to request?

Water use

Electrimetric is about quantifying our resource and energy consumption and using that knowledge to direct our choices for more efficient use of those resources and reduction in energy consumption. The name may imply electricity, but water is a key resource and likely to be "the next oil" as it becomes increasingly scarce.

A product design I saw on inhabitat (a great architecture and design blog that focuses on green and pre fab) is a meter for faucets to see how much water is being used. The theory goes that if are reminded as to how much you are using you will use less. It seems to just be a design/prototype right now but I think it would be great if it becomes a real product.